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12-29-2007, 12:12 PM

#301

lsx24

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Bassani Dual Exhaust

Description

My dual exhaust project utilized the Bassani Tru-Dual exhaust. This is an excellent implementation. I drove with this setup extensively and credit it to have very good qualities: Tangible gains, stainless steel construction, clean deep tone. Bassani's dual exhaust is objectively and subjectively an extraordinary dual exhaust implementation. For quantitative results I did before/after dyno testing at ProDyno, starting with jba shorties and factory ypipe/magnaflow catback. This combo put down a SAE corrected 345 rwhp 325 rwtq with a canned tune. With installation the guys at Pro Dyno (Charles is a regular consultant on the hit television show PINKS) did a perfect job. They dynoed the car and showed a corrected gain of 18 lb/ft midrange. The final numbers came out to a corrected 344 rwhp 343 rwtq though the noticeable difference in midrange was the exemplary factor, with a clean, deep tone.

Then I had the setup re-dynoed at an independent dyno, Carolina Auto Masters, where it produced a corrected 343 rwhp 349 rwtq with the same combo. Those numbers are no small feat for a setup that consisted of jba headers/complete induction (S1 ported ls6, no FAST). Especially the tq numbers. This is LongTube header territory. I would have had more peak hp if the stock cam and valvetrain didn't start to float though anything approaching at or above these numbers are tangible. Then to prove a theory I installed a Dynomax Ultraflow dual-in dual-out muffler to replace Bassani's muffler. This design tweak resulted in no gain on the dyno. Looking closely at the graph there was a loss of 3 hp peak and at low rpms. I didn't take the time to retune with Jeff at CAM, however fluid dynamics suggests Bassani's configuration's effectively optimal. In conclusion, the system is a result of various R&D elements producing tangible results, with implementation and sound the deciding factors.

Notes

In the Prodyno graph the peak tq is noticeably less than the peak tq at CAM. The reason is the relative environmental conditions in AZ result in quantifiably lower peak numbers. In the CAM graph the Bassani combo was dynoed at a more consistent geographic location where relative environmental variables exemplify accuracy.
In the back-to-back graph taken a few days apart there's no peak hp gain. Basically this combo isn't cat-back limited, therefore the existing cat-forward capacity results in similar peak hp even with additional exhaust system cfm capacity.
As far as loss of low end tq from muffler replacement concisely the resulting tune of the subsequent combo isn't optimal for a complex dual exhaust system. For completion purposes the next step should be a wideband tune/retune where the results of system dynamics would yield analysis conclusions.

Summary